Tap head bolt / intake bolt holes on rebuild?

[Craig Nedrow]

As a retired machinist, I can tell you about taps, and there is a big spectrum. Cast iron blocks have graphite, which is by nature slippery, machinist handbook lists a few things to use for lube. I like black sulfur based cutting oil, can use it for most materials, except, some aerospace and nuclear industry. Also kerosene and black oil excellent in aluminum. You have straight, spiral, former, spiral point and etc, each designed to do a certain job, in certain materials. Taps are made in three tapers, tapered, plug, and bottom, with the majority being the plug style. Bottom taps will get the job done, but require much more torque, because there is less lead in, conversely, taper style has less torque because of the long taper. Torque is what breaks taps, that and dry tapping. Good brand taps: Greenfield, Cleveland, Accupro good less expensive tap, Guhring, Emug highest quality, but you won't be needing them, here for comparison. HF, junk, Irwin barley ok. I probably have close to 500 taps in the shop, can tap anything, so having said that, buy good high speed steel (NOT CARBON STEEL) plug tap and a good tap wrench. Here are a few pics, as they tell the story, and while SS bolts really do not work, better grade 8 or 10 and ground with a hook (positive rake angle), NOT A FLAT, will nor cut, but may form softer non ferris materials, personal experience. Pic 1) right hand cutting, spiral point (pushes the chips forward, or down) , plug style, shows the positive rake. 2) Spiral tap, used in softer materials pulls the chip out like a drill, either plug or bottom style. Tap handles, top greenfield, it is about fourty years old, tapped thousands of holes, comes in several sizes, expensive, but worth it. Bought mine used at Boeing surpluses, Auburn WA. Middle is homemade, also fourty years old, still has it's uses. Bottom, General brand ratchet tap handle, also fourty years old, and excellent choice for the home shop, make two sizes, have them both. Bottom is a specialized tap, it is a former tap, forms (like forges) the thread making the metal denser, there for stronger as much as 30%. Used mostly in non ferris applications requires a larger tap drill.

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[Ricko1966]

You understand he's just chasing threads that probably have nothi g in them to begin with. He is not tapping holes.And stainless bolts as chasers ground with a flat do work, not cutting, chasing.Personal expierience.

 

[Craig Nedrow]

Yes tap every torqued bolt hole so torque values are correct with the recommended lube. ARP requires there proprietary lube to achieve correct torque values for there bolts as an example. Broken taps can be removed, have done it hundreds of times, saying that to say this. Here's what breaks taps: wrong tap drill, tap bottoming out, not cleaning out the chips on sprial point, or not enough clearance for the chips in the bottom of the hole, wrong type tap for the job, wrong cutting fluid. There ya go.

 

[GXPWeasel]

You understand he's just chasing threads that probably have nothi g in them to begin with. He is not tapping holes.And stainless bolts as chasers ground with a flat do work, not cutting, chasing.Personal expierience.

Yep, this is exactly what I wanted, and therefore did yesterday.
I purchased the 2 sizes of stainless bolts needed ($9 investment). I ground a groove approx 3/4" to 1" up the threads, which left a void in the bolt. I then used only finger pressure to chase all head bolt holes, intake bolt holes, water pump holes, and exhaust bold holes. There were probably 5 total holes that I did run into some crud / dirt that clearly filled the grove I cut in the bolt. Most holes were just oil, which I put in the holes before I chased them.

This worked great, probably wasn't completely needed, but for the $9 investment, it gave me great peace of mind.

 

[Craig Nedrow]

You understand he's just chasing threads that probably have nothi g in them to begin with. He is not tapping holes.And stainless bolts as chasers ground with a flat do work, not cutting, chasing.Personal expierience.

Not well in my experience, and diffidently not with a flat, maybe with a hook. Yes I have done this, but run a bolt down on a thread like that and it will still be stiff. do the same hole with a tap, and some chips will come out, and the bolt will be nice and smooth for the entire engagement. Not trying to step on any toes here, but this is accurate information gathered over many years experience. Go here for more info:
https://www.mscdirect.com/browse/lookahead/?searchterm=taps&hdrsrh=true

 

[Craig Nedrow]

Another good resource

https://www.mscdirect.com/basicsof/high-performance-taps

 

[Ricko1966]

I didn't mean to step on anyone's toes either.I worked in automotive including Machine shop fo over 30 years I learned that trick at work probably about 1990 and have done it for years since then with no trouble.ARP with their head studs and bolts say to use a chaser and their special lube, sorry, I just use oil.And I have remove plenty of broken taps I never said it can't be done I said sometimes it's a bit#h about once a month we'd get some ones cylinder head or intake manifold with a tap broke off in it and 1/2 the time they already wallered the top side of the hole out trying to drill it out before they brought it to us.It was always user error, cheap taps, etc.

Sorry if I offended you.

And sir you may be right maybe grinding them a different way would work a little better, but this was how I was taught and has worked well for me for 30 years

 

[MikeB]

You are right, don't chase threads with taps. I have a full set that I've been using for years just like this one:
https://www.tooltopia.com/Lang-Tool...zl2Ffn_ZsYQ9khk7xHHIKCC0fZVgutLxoC1xQQAvD_BwE

That's a nice set!

Did you read where I said and pictured to grind a flat to collect chips? Stainless is harder than mild steel or the scrap in the threads and will chase them just fine. Try it sometime.

I'll try it if I ever need to chase some fine threads or metric threads.

 

[MikeB]

To the OP: On another note, be sure to run a brush through the oil galleries. And wipe down the cylinders with white paper towels and oil until you don't see any discoloration. The grit left over from honing builds up in the cross hatch and can cause abrasion of the coatings on the rings.

There's a small chance the machine shop thoroughly cleaned the block, but never ASSume anything. In fact, you should ask them what they recommend.

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[GXPWeasel]

To the OP: On another note, be sure to run a brush through the oil galleries. And wipe down the cylinders with white paper towels and oil until you don't see any discoloration. The grit left over from honing builds up in the cross hatch and can cause abrasion of the coatings on the rings.

There's a small chance the machine shop thoroughly cleaned the block, but never ASSume anything. In fact, you should ask them what they recommend.

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Yep, I got the full recommendation from the shop on how to clean the block before I started assembly. He told me they do the work, parts wash, then spray down with oil so that things won't rust, but he admitted that it's not ready for assembly then. I'll need to clean it. I could tell I'd have to do this anyway, because by the time I got this back to the shop, just the ride in the bed of my truck (covered with a tonneau cover) was dirty enough to leave dust/dirt/residue on the cylinder walls.

I'll give it a good wipe down for sure before I start.